Hydrophilic copolymers have been used in the past to make soft contact lens, e.g., see Wichterle Reissue Pat. No. 27,401 which shows, for example, the use of a sparingly cross-linked copolymer of a hydrophilic monoester of acrylic or methacrylic acid and dihydric alcohol with a minor amount of diester of a dihydric alcohol and acrylic or methacrylic acid.
More recently, it has been proposed to make a hydrophilic lens from a cross-linked copolymer of an N,N-(C.sub.1 -C.sub.2 alkyl)acrylamide and a C.sub.1 -C.sub.4 alkyl acrylate or methacrylate, see Schultz U.S. Pat. No. 4,067,839. The entire disclosures of Schultz and Wichterle are hereby incorporated by reference and relied upon.